SELECT * FROM users;
-- 添加用户
insert into users(username,password) values('pcsb','123456');

-- 删除用户 
delete from users where id = 1;

-- 修改用户
-- update users set password='778899' where id=1;
-- 更新 id为2 的用户 把密码和状态更新为 456456 1
update users set password='456456',status=1 where id=1;

-- 演示where 子句的使用alter
-- select * from users where status=1;
-- select * from users where id>1;
select * from users where id!=3;

-- 使用and 显示匹配条件的用户 必须满足所有条件
select * from users where status=0 and id>2;

-- 使用or 显示匹配条件的用户alter 条件是满足一个条件就可以
select * from users where status=0 or id>2;

-- order by 排序 升序ASC 降序DESC
select * from users order by id desc;

